Downhole vibration tool

ABSTRACT

A downhole vibration tool has an outer housing having an inner surface that defines an inner bore and a flow diverter positioned within the inner bore, the flow diverter having an inner passage and an outer surface that defines a flow path between the inner surface of the outer housing and the flow diverter. A removable plug blocks the inner passage, the plug being removable to open the inner passage. A rotating member is rotatably carried within the outer housing and downstream of the flow diverter, the rotating member comprising a rotor in fluid communication with the flow path and an eccentric mass.

TECHNICAL FIELD

This relates to a downhole vibration tool, such as a vibration tool thatmay be included in a drill string.

BACKGROUND

Downhole vibrating tools are commonly used in drill strings to reducefriction during drilling. U.S. Pat. No. 7,708,088 (Allahar et al.)entitled “Vibrating downhole tool” describes a tool that uses aneccentric mass on an inner mandrel that is driven by turbine blades. Asthe mandrel rotates, the eccentric mass causes the tool and the drillstring to vibrate.

SUMMARY

According to an aspect, there is provided a downhole vibration tool,comprising an outer housing having an inner surface that defines aninner bore and a flow diverter positioned within the inner bore. Theflow diverter has an inner passage and an outer surface that defines aflow path between the inner surface of the outer housing and the flowdiverter. A removable plug blocks the inner passage, the plug beingremovable to open the inner passage. A rotating member is rotatablycarried within the outer housing and downstream of the flow diverter.The rotating member comprises a rotor in fluid communication with theflow path and an eccentric mass.

According to another aspect, the rotor comprises a plurality of turbineblades.

According to another aspect, the rotor comprises a single stage turbine.

According to another aspect, the eccentric mass is positioned within asealed chamber below the rotor.

According to another aspect, the flow path is radially concentric andoutside the inner passage.

According to another aspect, the rotating member comprises ports belowthe rotor that provide fluid communication between the flow path and theinner bore.

According to another aspect, the rotating member is supported by axialand radial bearings within the outer housing.

According to an aspect, there is provided a method of drilling,comprising the steps of providing a drill string having an inner bore,the drill string comprising a drill bit at a downhole end, a measurementwhile drilling tool adjacent to the drill bit, and a vibrating tool asdescribed above; pumping fluid through the inner bore of the drillstring, the fluid being diverted by the removable plug through the flowpath, the fluid operating the vibrating tool and the drill bit; removingthe plug to access the inner passage; and retrieving the measurementwhile drilling tool through the vibrating tool.

It will be understood that the above aspects may be combined in anyreasonable combination.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the followingdescription in which reference is made to the appended drawings, thedrawings are for the purpose of illustration only and are not intendedto be in any way limiting, wherein:

FIG. 1 is a side elevation view in section of the vibrating tool.

FIG. 2 is a schematic diagram of a drill string.

FIGS. 3 a-3 d are detailed side elevation views in section of thevibrating tool.

FIG. 4 is a detailed side elevation view of the plug seat after the plughas been removed.

DETAILED DESCRIPTION

A downhole vibrating tool, generally identified by reference numeral 10,will now be described with reference to FIGS. 1-3 d.

Referring to FIG. 2, downhole vibration tool 10 is part of a drillstring 100 that has a MWD (measurement while drilling) tool 102 adjacentto a drill bit 104. Downhole vibration tool 10 is used to enhance theoperation of drill string 100 as it drills a borehole.

Referring to FIG. 1, downhole vibration tool has an outer housing 12with an inner surface 14 that defines an inner bore 16 and a flowdiverter 18 positioned within inner bore 16.

Flow diverter 18 has an inner passage 20 and an outer surface 22 thatdefines a flow path 24 between inner surface 14 of outer housing 12 andflow diverter 18. Flow path 24 has upper ports 26 and lower ports 28,each in communication with inner bore 16. Preferably, flow path 24 isconcentric with and outside inner passage 20 within outer housing 12. Aremovable plug 21 is positioned to block the inner passage 20. Plug 21is removable to open inner passage 20, such as to provide access throughflow diverter 18. Preferably, plug 21 allows access to the full boreinner diameter when removed. This may be done to provide access to drillstring 100 below vibration tool 10. For example, this may be done toaccess MWD tool 102 or drill bit 104.

A rotating member 30 is rotatably carried within outer housing 12 anddownstream of flow diverter 18. Rotating member 30 has a rotor 32 influid communication with flow path 24 and an eccentric mass 33 and flowports 28 below rotor 32. It has been found that diverting fluid throughthe flow path 24, which is outside the bore, the effects of washing, orerosion caused by abrasives in the drilling fluid, is reduced.

As shown, flow diverter 18 has a first portion 34 that is threaded intoouter housing 12 and locked into place such that it cannot be rotatedand a second, and an inner portion 36 that is removed with plug 21. Ascan be seen, inner portion 36 has a locking piece 37 that engages aninner surface of flow diverter 18. As locking piece 37 is released, plug21 and second portion 36 are free to be removed. Preferably, referringto FIGS. 3 a and 3 b, second portion 36 is sealed against first portion34 by seals 38 and second portion 36 seals against plug 21 by seals 40when received. Seals 38 and 40 are used to ensure the fluid flowsthrough flow path 24. Second portion 36 also extends downward from flowdiverter 18 and engages rotating member 30. As shown, seals 42 areprovided that seal between rotating member 30 and second portion 36.

Referring to FIG. 3 b, plug 21 has a fishing neck 39 that allows afishing tool (not shown) to grip and remove plug 21. As plug 21 isremoved, inner portion 21 is also removed. Referring now to FIG. 4, byremoving inner portion 36 and plug 21, vibration tool 10 is able toprovide “full bore” access to the rest of drill string 100, as indicatedby the broken lines.

In one example, flow diverter 18 has stators 44 in flow path 24 thatdirect the fluid onto rotor 32, which may be a turbine 46 with a singlestage of turbine blades. While there may be more than one stage, it hasbeen found that a single stage provides for higher speed, particularlyat low pressure, due to the lower weight compared to the conventionalpractice of using multiple stages. While multiple stages increasestorque, it also results in a lower speed. In addition, a single stageblade design allows for higher solid contents or LCM content in thedrilling fluids pumped through inner bore 16. Preferably, the turbineblades are removable and can be replaced with a different pitch or withmore stages.

Referring to FIGS. 3 b and 3 c, eccentric mass 26 is carried below rotor32 in a sealed chamber 48. Eccentric mass 26 rotates with rotor 32 andprovides radial vibrations that, in a drilling operation, make theoperation more efficient by reducing the necessary torque withoutinterfering with typical drilling operations and without transmittingvibrations to the surface or bit. While not required, housing eccentricmass 26 in sealed chamber 48 instead of open to inner bore 16 may bepreferred in some circumstances to allow for more efficient operation byreducing the friction during rotation and help reduce pressure loss. Asis known, chamber 48 is balanced to reduce any hydrostatic build up. Asshown in FIG. 3 c, bearing surfaces 50 are provided above and beloweccentric mass 26 to properly support the rotation of eccentric mass 26.Bearing surfaces 50 as shown are radial and axial bushings, which havesome size advantages given the limited space available. Other bearingsurfaces, such as roller bearings could also be used if desired. Thelower bearing surfaces 50 are supported from the bottom by a threadedcollar 52 and are held stationary relative to outer housing 12.

According to an aspect, there is provided a method of drilling,comprising the steps of providing a drill string having an inner bore,the drill string comprising a drill bit at a downhole end, a measurementwhile drilling tool adjacent to the drill bit, and a vibrating tool asdescribed above; pumping fluid through the inner bore of the drillstring, the fluid being diverted by the removable plug through the flowpath, the fluid operating the vibrating tool and the drill bit; removingthe plug to access the inner passage; and retrieving the measurementwhile drilling tool through the vibrating tool.

In this patent document, the word “comprising” is used in itsnon-limiting sense to mean that items following the word are included,but items not specifically mentioned are not excluded. A reference to anelement by the indefinite article “a” does not exclude the possibilitythat more than one of the elements is present, unless the contextclearly requires that there be one and only one of the elements.

The scope of the following claims should not be limited by the preferredembodiments set forth in the examples above and in the drawings, butshould be given the broadest interpretation consistent with thedescription as a whole.

What is claimed is:
 1. A downhole vibration tool, comprising: an outerhousing having an inner surface that defines an inner bore; a flowdiverter positioned within the inner bore, the flow diverter having aninner passage and an outer surface that defines a flow path between theinner surface of the outer housing and the flow diverter; a removableplug that blocks the inner passage, the plug being removable to open theinner passage; and a rotating member rotatably carried within the outerhousing and downstream of the flow diverter, the rotating membercomprising a rotor in fluid communication with the flow path and aneccentric mass.
 2. The downhole vibration tool of claim 1, wherein therotor comprises a plurality of turbine blades.
 3. The downhole vibrationtool of claim 1, wherein the rotor comprises a single stage turbine. 4.The downhole vibration tool of claim 1, wherein the eccentric mass ispositioned within a sealed chamber below the rotor.
 5. The downholevibration tool of claim 1, wherein the flow path is radially concentricand outside the inner passage.
 6. The downhole vibration tool of claim1, wherein the rotating member comprises ports below the rotor thatprovide fluid communication between the flow path and the inner bore. 7.The downhole vibration tool of claim 1, wherein the rotating member issupported by axial and radial bearings within the outer housing.
 8. Amethod of drilling, comprising the steps of: providing a drill stringhaving an inner bore, the drill string comprising a drill bit at adownhole end, a measurement while drilling tool adjacent to the drillbit, and a vibrating tool connected in the drill string, the vibratingtool comprising: an outer housing having an inner surface that definesan inner bore; a flow diverter positioned within the inner bore, theflow diverter having an inner passage and an outer surface that definesa flow path between the inner surface of the outer housing and the flowdiverter; a removable plug that blocks the inner passage, the plug beingremovable to open the inner passage; and a rotating member rotatablycarried within the outer housing and downstream of the flow diverter,the rotating member comprising a rotor in fluid communication with theflow path and an eccentric mass; pumping fluid through the inner bore ofthe drill string, the fluid being diverted by the removable plug throughthe flow path, the fluid operating the vibrating tool and the drill bit;removing the plug to access the inner passage; and retrieving themeasurement while drilling tool through the vibrating tool.
 9. Themethod of claim 8, wherein the rotor comprises a plurality of turbineblades.
 10. The method of claim 8, wherein the rotor comprises a singlestage turbine.
 11. The method of claim 8, wherein the eccentric mass ispositioned within a sealed chamber below the rotor.
 12. The method ofclaim 8, wherein the flow path is radially concentric and outside theinner passage.
 13. The method of claim 8, wherein the rotating membercomprises ports below the rotor that provide fluid communication betweenthe flow path and the inner bore.
 14. The method of claim 8, wherein therotating member is supported by axial and radial bearings within theouter housing.